Colloid engine beam thrust vectoring

ABSTRACT

To provide thrust vectoring in a colloid beam engine, a plurality of deflector electrodes surround the colloid needles upstream of the extractor. To change the direction of the colloid beam, a bias voltage is applied to the deflector electrodes whereby to vary the thrust vector of the colloid beam.

United States Patent [191 1 Kidd et al.

[ COLLOID ENGINE BEAM THRUST VECTORING [75] Inventors: Philip W. Kidd,Palos Verdes Peninsula; Norman E. Law, Cypress,

both of Calif.

[73] Assignee: TRW lnc., Redondo Beach, Calif.

[22] Filed: Oct. 23, 1970 [21] Appl. No.: 83,486

[52] US. Cl. 60/202, 60/230 [51] Int. Cl. H05h 5/00 [58] Field of Search60/203, 202, 228,

[56] References Cited UNITED STATES PATENTS 3,122,882 3/1964 Schultz60/202 3,535,880 10/1970 Work et al 60/230 X 2,880,337 3/1959 Langmuiret a]. 60/202 3,273,337 9/1966 Bolieau 60/256 [4 Aug. 28, 1973 3,071,1541/1963 Cargill et a1. 60/230 3,304,718 2/ 1967 Webb 60/202 R26,1773/1967 Deutsch 60/202 3,537,266 11/1970 Mahadevan et a1. 60/2023,238,715 3/1966 Reader et a1. 60/202 3,286,467 Ill 1966 Hunter 60/2023,233,404 2/ 1966 Huber et a1 60/202 3,512,362 5/1970 Daley 60/202Primary ExaminerCarlton R. Croyle Assistant Examiner-Robert E. GarrettAttorney-Daniel '1". Anderson, Donald W. Graves and William B. Leach 571ABSTRACT To provide thrust vectoring in a colloid beam engine, aplurality of deflector electrodes surround the colloid needles upstreamof the extractor. To change the direction of the colloid beam, a biasvoltage is applied to the deflector electrodes whereby to vary thethrust vector of the colloid beam.

3 Claims, 4 Drawing Figures Patented Aug. 28, 1973 Philip W. Kidd NormanE. Law

INVENTORS BY M ATTORNEY 1 COLLOID ENGINE BEAM TIIRUST VECTORINGBACKGROUND OF THE INVENTION This invention relates to a thrust producingdevice such as a rocket engine. Rocket engines consist of many varioustypes such as the conventional bipropellant or monopropellant engine, asolid propellant engine and the hybrid engine which uses a monoliquid orgaseous propellant and a solid propellant.

Other types of engines include the nuclear engine which operates byheating a propellant such as hydrogen by means of a nuclear source.Another type of engine which has been utilized is the plasma enginewhich forces ions of a gaseous plasma material into space thus producingthrust.

The choice of which type of rocket engine to use for variousapplications depends on various factors. One of these factors isexpense. Another factor may be whether the engine is to be used as abooster to lift a rocket off the ground while another factor is thespecific performance of the various engines particularly when consideredas a trade off between the desired specific performance and the weightof the engine and expense and whether the engine is operated undervacuum conditions or in the booster phase.

Still another type of engine is the so called colloid beam engine whichoperates under the principle of providing an electrical bias on a liquidpropellant containing or consisting of a metal whereby the propellant isaccelerated thus providing thrust for the engine. The advantage of thecolloid beam type engine is the high specific performance obtainedtherefrom in space applications, particularly over long periods of time.

One of the desired capabilities of a rocket engine and in particular acolloid beam engine is the ability to vary the thrust vector. That is,to change the direction of thrust whereby a spacecraft can be maneuveredwhere desired.

Previous attempts to provide thrust vectoring of a colloid beam engineincludes mechanically vectoring the engine itself whereby to change thedirection of thrust. This has inherent problems, however, in that arelatively heavy mechanical complicated vectoring system must beprovided to physically change the direction of thrust which consists inmoving the engine itself or at least a portion thereof.

Another approach to providing thrust vectoring of the colloid beamengine has been to provide an electrostatic deflection of the chargedparticle beam. This has been done by placing plates downstream of theextractor plate of the colloid engine itself and applying a voltage tothe plates. The problem with this construction is that in order to getreasonable thrust vector deflections, the plates must extend aconsiderable distance downstream from the engine which adds considerableweight to the module and in addition renders the plates unprotected fromsecondary currents produced downstream.

SUMMARY OF THE INVENTION This invention can be summarized as comprisinga colloid thrustor engine which has at least one propellant feed needleand an extractor plate having apertures therein which is adapted toaccelerant the propellant from the needle through the apertures in theplate in response to a voltage bias on the plate relative to the needleand in addition which includes at least one deflector electrode locatedadjacent at least one side of the needle upstream of the propellant flowthrough the extractor plate and which is adapted to have a voltage biasapplied to the deflector electrode whereby the propellant vector isvaried at will depending upon the bias applied to the deflector plate inrelationship to the needle voltage and the extractor plate voltage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partially in crosssection of a colloid engine constructed according to this invention asviewed along the lines ll of FIG. 2,

FIG. 2 is a view of the downstream end of the colloid engine as viewedalong the lines 22 of FIG. 1,

FIG. 3 is an enlarged view looking along the axis of one of the colloidneedles surrounded by the vector electrodes and FIG. 4 is a viewpartially in cross section illustrating the arrangement of a singleneedle and a single vector electrode.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Shown generally at 2 is acolloid beam thrustor constructed according to this invention. Thiscolloid beam engine has an outer casing 4 which is typically constructedof a material such as an epoxy resine. This sup port or outer containersupports the various vector electrode supports 6 which typically areconstructed of a metal such as copper or stainless steel. This is moreclearly seen in FIG. 4. One of these vector electrode supports is shownsupporting one of the various vector electrodes 8. Additional supportsare held in slots 7. Also supported by container 4 is the extractorplate 12 which is also constructed of a metal such as stainless steeland has a plurality of apertures 14 therein. Each of these apertures isaligned with the vector electrodes 8 and 10 and needles 16 which aresupported by needle holders I8 which are typically constructed ofcopper. The needles themselves are constructed of platinum iridiumtubing which is soft soldered in the holder 18. The needle holders 18are in turn encased in a base plate 20 which is held in place both bycontainer 4 and an insulator 22 constructed of a material such asteflon.

A plurality of metallic conductors 24 are attached to base plate 20. Abias line or conductor 26 leads through insulator or outer container 4to the extractor plate 12, while vector bias lines 28 and 29 areconnected to the various vector electrode metal supports. Leads 30 arein a similar fashion connected to conductors 24 whereby to provide abias to the needle holders and in turn to the needles 16. An annularring 32 is provided which may be constructed of metal. If so, lead 30would be merely connected thereto rather than extending through the baseplate layer 24, but if constructed of an insulator would be as shown inFIG. 1. This annular ring in turn supports the structural member 34which contains a propellant passage 36. A plenum chamber 38 is shownwhich contains a millipore filter 37 to prevent sedimentation in theneedles and in the example shown is a 1.5 micron filter. There are sixlongitudinal bars 24 each of which are connected to six needles [6through supports 18.

A thermocouple 40 is provided to measure the temperature and a heaterelement 42 is shown to heat the engine. When a propellant such asNaI-glycerol is used, the viscosity changes by approximately 10 percentfor a 2 C variation around the temperature of 24 C. Therefore, athermocouple and heating element is provided to maintain the temperatureat a relatively constant level.

In normal operations of engines of this type, a propellant is introducedinto line 36, chamber 38 and through millipore filter 37 and thence pastbars 24 and through needles 16. A positive bias from a source not shownthrough lead 30 biases bars 24, needle holders l8 and needles [6 at ahigh positive bias such as approximately 7 kilivolts. This figure is notcritical but is given as an example only.

In turn, the extractor plate 12, by means of bias 26, is maintained at anegative voltage such as minus 300 volts. When propellant is fed throughconduit 36 under a relatively slight pressure, the negative bias ofextractor plate 12, in combination with the positive bias of the liquidpropellant which may consist of Nal-glycerol or glycerol-Kl or otherliquid metals such as cesium or gallium will be accelerated at a highrate and pass out through needle 16 to provide thrust. As an example,utilizing a single module such as shown in FIG. 2 which contains 36needles, a combination of eight modules resulting in 288 needles with athrust of 2.5 micro pounds per needle will result in a specificperformance at approximately 1,000 2,000 seconds with a powerexpenditure of 23 watts. Specific performance is defined as the ratio ofthe thrust measured in pounds divided by the mass flow rate, measured inpounds of the propellant per unit of time (seconds). This is a commonmeasure of performance of a rocket engine and is commonly known as lsp.

Thus far described, the operation of this engine is relativelyconvention. As previously stated, it is often desirable to have anengine which can be vectored so as to change the direction of thrust.The methods heretofore proposed have been relatively unsatisfactory andthe disadvantages of these methods have been overcome by the instantinvention.

Lines 28 and 29 (six of each) are each connected to alternate vectorelectrodes 8 and 10. The voltage divider network, not shown, is providedwhereby the bias difference between the vector electrodes 8 and isroughly 1/7 that of the voltage bias applied to the needles 16. Thus, inthe instant example, there would be a voltage difference of roughly 1kilivolt between the vector electrodes 8 and 10. When this bias isapplied, the colloid beam exiting needle 16 will be at an angledifferent from the axis of the colloid thrustor as shown by line 46.This provides a vectoring effect and is capable of changing thedirection of thrust of the engine. Since there is no drainage of currentbetween the vector electrodes, the power requirements are essentiallyzero.

In addition to the capability of deflecting the colloid beam, the vectorelectrodes can also be used to focus and stabilize the beam as well asadjusting the lsp.

What is claimed is:

1. In a colloid thruster engine having a plurality of propellant feedneedles and an extractor plate having a like plurality of aperatureseach associated with one of said plurality of needles and adapted toaccelerate propellant from said plurality of needles through said likepluraltiy of aperatures in said plate in response to a voltage biasbetween said plate and said plurality of needles, that improvement whichcomprises:

a plurality of deflector electrodes each located adjacent one side ofone said plurality of needles at a point upstream of the propellant flowthrough said extractor plate, each said deflector electrode beingadapted to have a voltage bias applied thereto; whereby the direction ofthe propellant vector is varied so as to vary the direction of thethrust vector of the engine.

2. A method of providing thrust to a colloid thruster engine whichcomprises:

introducing an electrical conductive propellant at a high positivevoltage bias through a plurality of needles toward an extractor plate ata negative bias, the resultant colloid beam thereby producing a thrustvector; and

applying the field of an intermediate voltage bias to at least one ofthe plurality of needles at a point upstream of the propellant flowthrough the extractor plate; whereby the direction of the colloid beamis varied so as to vary the direction of the thrust vector of theengine.

3. A method according to claim 2 in which said intermediate voltage biasmay be varied so as to vary the thrust vector of said colloid beam. =1

1. In a colloid thruster engine having a plurality of propellant feedneedles and an extractor plate having a like plurality of aperatureseach associated with one of said plurality of needles and adapted toaccelerate propellant from said plurality of needles through said likepluraltiy of aperatures in said plate in response to a voltage biasbetween said plate and said plurality of needles, that improvement whichcomprises: a plurality of deflector electrodes each located adjacent oneside of one said plurality of needles at a point upstream of thepropellant flow through said extractor plate, each said deflectorelectrode being adapted to have a voltage bias applied thereto; wherebythe direction of the propellant vector is varied so as to vary thedirection of the thrust vector of the engine.
 2. A method of providingthrust to a colloid thruster engine which comprises: introducing anelectrical conductive propellant at a high positive voltage bias througha plurality of needles toward an extractor plate at a negative bias, theresultant colloid beam thereby producing a thrust vector; and applyingthE field of an intermediate voltage bias to at least one of theplurality of needles at a point upstream of the propellant flow throughthe extractor plate; whereby the direction of the colloid beam is variedso as to vary the direction of the thrust vector of the engine.
 3. Amethod according to claim 2 in which said intermediate voltage bias maybe varied so as to vary the thrust vector of said colloid beam.